One Night, Two Spaceships

Sky watchers in North America can spot the ISS and
the space shuttle Atlantis at the same time on Oct. 16 and 17.

October 16, 2002: It's not every night you get to see
a spaceship fly over your back yard. This week you can see two.

The International Space Station (ISS) and the space shuttle
Atlantis will soar over North America after sunset on Oct. 16th
and again on the 17th. It's perfect timing for sky watchers.
Light from the setting sun will glint off the two spacecraft
and make them easy to spot.

Above: Using an 8-inch telescope and an inexpensive
digital camera, Tom Gwilym of Bellevue, Washington, captured
these images of the ISS and the space shuttle docked together
on Oct. 13th.

Just this morning Atlantis undocked
from the space station--the end of its 9-day visit to the ISS.
The single point of light which in recent days had been the two
spaceships joined together has now split in two. Until Atlantis
lands on Oct. 18th, the shuttle will follow an orbit similar
to the space station's. This means you can see both spaceships
at the same time (or nearly so) as they pass overhead in tandem.

Peering at the ISS through a telescope can be a wonderful
experience. (Amateur astronomer Ulrich Beinert explains how to
do it in the Science@NASA story "More
Spaceship Sightings.") The space station's T-shaped
solar arrays are eye-catching, and many sky watchers are impressed
by their eerie copper color.

You don't, however, need a telescope to enjoy these flybys.
The station will be very bright and easy to see with the unaided
eye.

When exactly should you look?

Find out by visiting one of these three popular web sites:
J-Pass,
Heavens Above, or
SkyWatch.
Each will ask for your zip code or city, and respond with a schedule
of suggested spotting times. Times for selected US cities are
listed in the table below. It's a partial list. If your home
town is not included, check the web sites for more information.

Space Station Spotting
Times for Selected US Cities
Click on any city name to see a sky map of that city's flyby.
(Courtesy of Heavens
Above)

Above: Local times in October when the ISS will appear
over some U.S. cities. The station will emerge over the northwest
horizon, sail overhead (or nearly so), and disappear again in
the southeast.

A typical apparition looks like this: The space station appears
near the horizon. At first it's just a dim speck of light, but
it brightens as it glides overhead, crossing the sky in 3 to
6 minutes. When the geometry is right, as it will be for many
sky watchers on Oct. 16th and 17th, the ISS outshines every star
in the sky except the sun.

Although the space shuttle is smaller than the ISS, it will
shine brighter than the ISS during the coming flybys. Why? The
shuttle's white surface is an excellent reflector of sunlight.
The two brilliant spacecraft will appear close together on Oct.
16th, but farther apart on the 17th as Atlantis prepares to land.
Heavens Above calculates
sighting times for the ISS and the shuttle. Check both before
you head outdoors.

The crew of the Atlantis have been working at the ISS this
past week on a construction mission. They delivered and installed
the S1-truss, a 45-foot-long extension to the station's "backbone."
Attached to the S1-truss is a
radiator, silvery and reflective, which itself unfolds 75-ft
long. Every time such pieces are added to the expanding station,
it becomes easier to see.

That's good news for sky watchers because the ISS soaring
overhead is a lovely sight. The space shuttle flying nearby only
makes it better. Check the flyby schedule for your hometown and
see for yourself!

more information

NASA's
Human Spaceflight
-- (SpaceFlight.nasa.gov) Up-to-date information about the space
shuttle and the International Space Station.

A helpful
hint: Web sites like
Heavens Above will
give you a list of spotting times for your hometown. Usually
its a long list. Which times should you choose? The best apparitions
are the ones with negative
magnitudes. The astronomical brightness scale works like
this: A 1st magnitude star is bright. A -1st magnitude star is
much brighter. The more negative the better. The magnitude of
the Sun, for example, is -26. try looking for the ISS anytime
its magnitude is less than zero.

Right: The brightly-lit International Space Station
in April 2002. [more]

What makes the ISS shine? There are no bright lights on the outside
of the space station. The ISS shines by reflecting sunlight,
as much as 90% of the light that hits it. Much of the ship is
light-colored. Even the awesome solar arrays, which must absorb
sunlight to power the station, aren't completely black. Their
reflectivity is near 35%.

What is a "truss?" -- from spaceflight.nasa.gov, includes
an interactive diagram of the space station's growing infrastructure.